Primary ciliary dyskinesia
Definition
Rare autosomal recessive disorder characterized by absent or dysmotile cilia caused by a defect in the dynein arm of microtubules.
Etiology
Pathophysiology
Dynein: a class of motor proteins that convert cellular energy to mechanical energy. They allow for migration, propagation, and movement of cells/organelles usually along the microtubules.
Clinical features
- Chronic productive cough
- Recurrent otitis, sinusitis, and nasal polyps
- Bronchiectasis
- Conductive hearing loss
- Displaced heart sounds (as a result of dextrocardia)
- Infertility in men due to decreased sperm motility as a result of defective flagella
- Reduced fertility in women (and rarely ectopic pregnancy) due to defective cilia in fallopian tubes
- Kartagener syndrome: classic triad of situs inversus, recurrent sinusitis, and bronchiectasis
Mnemonic
You can memorize the cause of Kartagener syndrome by thinking of Kartagener's restaurant that only has 'take-out' service because there is no dine-in (dynein).
Diagnostics
- Nasal nitric oxide test: reduced nasal nitric oxide (screening test)
- Ciliary beating is thought to play a role in stimulating nitric oxide synthase (NOS), the enzyme responsible for NO production
- Genetic tests for dynein arm mutations
- Chest x-ray: bronchiectasis, dextrocardia, and situs inversus (suggests Kartagener syndrome)
Tip
Same pulmonary symptoms and infertility like cystic fibrosis